Macro photography

thumb|right|upright=1.2|A dedicated macro lens, such as the [[Vivitar Series 1 90 mm shown here, is one of multiple methods to achieve the large reproduction ratio required for photomacrography.]]

Macro photography, also called photomacrography or macrography, and sometimes macrophotography, is extreme close-up photography in which the subject is reproduced at greater than its actual size. Macro photographs usually feature very small subjects and living organisms like insects.

Definitions

The optical reproduction ratio is the subject size captured on the film frame (or image sensor) compared to the actual subject size, and is a function of the lens design. The optical magnification is equivalent to optical reproduction ratio. For example, an optical reproduction ratio of 1:10 means the image is recorded at th of the actual subject size, and the equivalent optical magnification is ×, 0.10×, or 10%.

thumb|right|[[Minolta Zoom-Rokkor 100–300mm lens with markings for reproduction ratio]]

Building on this, a macro lens is therefore a lens capable of optical reproduction ratios of 1:1 or greater (e.g., 2:1, 3:1, etc.). Rudolf Kingslake gives a broader definition of a macro lens as one "which is well corrected for use over a wide range of object distances."

Since the size of the image on the negative or image sensor rarely is the subject of discussion except in technical photography and film-based processes, the final image (e.g., as printed, displayed in a magazine, or on a web page) is a more relevant measure of displayed size. Define the final magnification (or final reproduction ratio) as the image size on the final print divided by the original object size. and so the final displayed image more commonly lends a photograph macro (i.e., >1:1) status. For example, when producing a print using an image captured on a 35 format (36×24 mm) film or sensor, the printing process results in an inherent 4:1 magnification in going from the sensor to the print, which means a life-size result is possible with a lens set at a 1:4 optical reproduction ratio.

{|class="wikitable floatright" style="font-size:90%;text-align:center;width:15em;"

|+Typical magnification ranges However, even 1:2 is significantly larger than non-macro lenses, as those often are designed with a maximum reproduction ratio (i.e., at closest focus) of approximately 1:10 for practical and optical considerations.

Development of the photo-micrograph led to the evolution of macro photography.

One of the earliest pioneers of macro photography was Percy Smith, born in 1880. He was a British nature documentary filmmaker, and was known for his close-up photographs.

Equipment and techniques

Macro lenses

thumb|right|[[Micro-Nikkor 55 mm Ai-S lens, at full barrel extension]]

Lenses with a "macro" focusing feature are specifically designed for close-up work, with a longer barrel extension mechanism than conventional lenses and optics optimized for high reproduction ratios; these are the most common tools for macro photography. and the effective focal length can be determined by comparing the observed lens extension for a given magnification to those same values at a reference point:

:<math>F_{eff} = \frac {\left ( d - d_{ref} \right )}{\left ( m - m_{ref} \right )}</math>

thumb|right|Canon MP-E 65 mm macro lens. Small front lens elements are typical of macro lenses.

True macro lenses offer a maximum optical reproduction ratio of 1:1 or greater, such as the Canon MP-E 65mm f/2.8 1-5x Macro, Laowa 25mm f/2.8 2.5-5X Ultra Macro (a relatively shorter focal length), Yasuhara Nanoha 4–5X, or Minolta AF 3x-1x f/1.7-2.8 Macro; by achieving higher magnification than life size, photographs can be taken of the structure of small insect eyes, snowflakes, and other minuscule objects. However, these lenses generally lose the ability to focus to infinity and cannot be used for general purpose photography. Others, such as the Infinity Photo-Optical's TS-160 can achieve magnifications from 0-18× on sensor, focusing from infinity down to 18 mm from the object.

Macro lenses are sold with different focal lengths for specific uses:

Continuously-variable focal lengthsuitable for virtually all macro subjects
"Normal" 45–65 mmgeneral purposes: product photography, document reproduction, small objects that can be approached closely without causing undesirable influence, and scenes requiring natural background perspective
"Portrait" 90–105 mminsects, flowers, and small objects from a comfortable distance
"Telephoto" 150–200 mminsects and other small animals where additional working distance is required

Mechanical extension

Extending the distance between the lens and the film or sensor, by inserting either extension tubes or a continuously adjustable bellows, is another equipment option for macro photography. As the lens is extended further from the film or sensor, the closest focusing distance decreases, the magnification increases in direct proportion to the lens extension; recall that <math>m=\frac{d}{F}</math>. In addition, the image exposure needs to be increased when focusing closer, whether by using a slower shutter speed or wider aperture.

thumb|right|This Nikon M2 extension tube provides 27.5 mm of extension and increases the maximum reproduction ratio of the 55 [[Micro-Nikkor to 1:1]]

For many "macro" lenses with a maximum optical reproduction ratio of 1:2, a specific accessory extension tube often is available with a fixed extension distance of ; with it mounted, the "macro" lens loses infinity focus but the focus range can be adjusted from 1:2 to 1:1.

Generally, extension tubes are rigid and provide a fixed increase in distance, and bellows are flexible, allowing a variable increase in distance. and Minolta Auto Bellows III. Other specialized perspective control lenses such as the Nikon PC-E and Canon TS-E series, the Hartblei Super-Rotator, the Schneider Super Angulon, several Lensbaby models, the Zoerk Multi Focus System, and various tilt-shift adapters for medium format, allow the use of tilt in cameras with fixed lens mounts.

Reversed and stacked lenses

Ordinary lenses can be used for macro photography by using a "reversing ring". This ring attaches to the filter thread on the front of a lens and converts the front thread to a conventional lens interface, which makes it possible to attach the lens in a reversed position on the camera body. Contemporary small-sensor digital cameras are equipped with high pixel density sensors and possess good resolving power due to advances in sensor technology, which enable them to capture very high levels of detail, rivaling the macro capabilities of a DSLR with a "true" macro lens, albeit often at the cost of greater image noise. Although the lenses fitted many small-sensor cameras have a lower reproduction ratio than a true macro lens (1:1), smaller sensors do not require the same optical reproduction ratio to produce identical framing and equivalent magnification, making macro photography more widely accessible at a lower cost.

In the digital age, a photograph is more practically defined as macro when an object measuring 24 mm or less either matches the frame's height or is larger.

Microscope attachments

thumb|upright=0.7|right|[[Wild Heerbrugg|Wild Macroscope with digital SLR on an optical tube separate from the stereo binocular viewer]]

Macro photography can also be carried out by attaching a camera to one optical path of a binocular microscope (stereo microscope), making use of the optics of that instrument as the imaging lens for the system. Between approximately 1976 and 1993, the manufacturers Wild Heerbrugg (Switzerland) and subsequently, Leica Microsystems offered a dedicated microscopy system for macro photography, the macroscope line, with improved optical performance for photography at the expense of the stereo imaging facility of the stereo microscope; this system came with a range of dedicated stands, objective and supplementary lenses, and illumination systems. Following its discontinuation in 1993, Leica continues to offer similar products under the names Z6 APO and Z16 APO.

File:Scatophaga stercoraria macro Luc Viatour.jpg|Common yellow dung fly (Scathophaga stercoraria) made using a lens at its maximum 1:1 reproduction ratio, and an 18×24mm image sensor, the on-screen display of the photograph results in a greater than life-size image

File:Dragon Fly portrait using reverse ring macro.png|Headshot of a dragonfly taken with a 100 mm macro lens coupled with a 50 mm lens in reverse at the end

File:Formica polyctena 2.jpg|Ant

File:Monarch fern sori.jpeg|A fern sorus using 4:3 aspect ratio

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35 mm equivalent magnification

35 mm equivalent magnification or reproduction ratio is a measure that indicates the apparent magnification achieved with a sensor format smaller than the 35mm film frame size of . The term is useful because many photographers are familiar with the 35 mm film format.

Because an image captured by smaller sensor needs additional magnification to achieve the same display size, an equivalent reproduction ratio can be achieved on a smaller sensor using a lens with a smaller reproduction ratio. Consider a situation where the photographer captures an object measuring 18×12mm at life size (reproduction ratio of 1:1) with a 35mm or "full-frame" camera, resulting in a recorded image with subject measuring 18×12mm (1:1), which occupies of the frame area (36×24mm). An equivalent photograph using a " sensor also would record the object into an area occupying of the frame, assuming the picture will be displayed at the same size. Since the frame size of the smaller sensor is approximately 18×13.5mm, the object would be captured at 9×6mm, which means the required reproduction ratio with the smaller sensor is 1:2, not 1:1.

For example, the 12 megapixel Micro Four Thirds Panasonic Lumix DMC-GH1 camera with a 2× crop sensor only requires a 1:2 reproduction ratio to take a picture with the same subject size, resolution, and apparent magnification as a 12 megapixel "full-frame" Nikon D700 camera, when the images are viewed on screen or printed at the same size. Thus a Four Thirds system macro lens like the Laowa 50mm f/2.8 2X Ultra Macro Lens with a maximum image magnification of 2.0× is rated as having a "4.0× 35 mm equivalent magnification".

To calculate 35 mm equivalent reproduction ratio, simply multiply the actual maximum magnification of the lens by the 35 mm conversion factor, or "crop factor" of the camera. If the actual magnification and/or crop factor are unknown (such as is the case with many compact or point-and-shoot digital cameras), simply take a photograph of a mm ruler placed vertically in the frame focused at the maximum magnification distance of the lens and measure the height of the frame. Since the object height of a 1.0x magnified 35 mm film image is 24 mm, calculate 35 mm equivalent reproduction ratio and true reproduction ratio by using the following:

:(35 mm equivalent reproduction ratio) = 24 / (measured height in mm)

:(True reproduction ratio) = (35 mm equivalent reproduction ratio) / Crop factor.

Since digital compact camera sensor sizes come in a wide diversity of sizes and camera manufacturers rarely publish the macro reproduction ratios for these cameras, a good rule of thumb is that whenever a 24 mm vertical object just fits, or is too tall to fit in the camera viewfinder, you are taking a macro photograph.

Lighting

thumb|right|The [[Micro-Nikkor#Medical|Medical-Nikkor line of lenses have an integrated ringlight to provide even close-up illumination]]

The problem of sufficiently and evenly lighting the subject can be difficult to overcome. Some cameras can focus on subjects so close that they touch the front of the lens. It is difficult to place a light between the camera and a subject that close, making extreme close-up photography impractical. A normal-focal-length macro lens (50 mm on a 35 mm camera) can focus so close that lighting remains difficult. To avoid this problem, many photographers use telephoto macro lenses, typically with focal lengths from about 100 to 200 mm. These are popular as they permit sufficient distance for lighting between the camera and the subject.

Ring flashes, with flash tubes arranged in a circle around the front of the lens, can be helpful in lighting at close distances. Ring lights have emerged, using white LEDs to provide a continuous light source for macro photography, however they are not as bright as a ring flash and the white balance is very cool.

Good results can also be obtained by using a flash diffuser. Homemade flash diffusers made out of white Styrofoam or plastic attached to a camera's built-in flash can also yield surprisingly good results by diffusing and softening the light, eliminating specular reflections and providing more even lighting.

Exposure adjustment

{|class="wikitable floatright" style="width:15em;font-size:90%;text-align:center;"

|+Effective aperture for typical magnifications which complicates the exposure compensation calculation. Cameras equipped with through-the-lens light meters should adjust the exposure based on the focusing distance and the amount of light passed to the metering sensor(s), although this may require stopping the lens down.